Recently, in silver halide light sensitive color photographic materials (hereinafter, also referred to as color photographic materials), two-equivalent couplers tend to be used, in which an appropriate substituent is introduced to the coupling position of the coupler (also called the active point) to react with an oxidized color developing agent, thereby reducing the number of silver atoms needed to form a dye molecule to two silver atoms, instead of the conventionally used four-equivalent couplers which needed four silver atoms to from a dye molecule.
However, requirements for couplers become more severe along with the progress of color photographic materials. Specifically, further improvements in dye formability are desired in terms of enhancements of sensitivity and image quality as well as rapid access.
Representative yellow dye forming couplers (hereinafter, also referred to as yellow couplers) include pivaloylaceto-anilide type yellow couplers and benzoylacetoanilide type yellow couplers. As is well known in the art, the benzoylacetoanilide type yellow couplers are generally superior in dye formability. However, commonly known benzoylacetoanilide type yellow couplers are inferior in solubility in solvents, producing problems in manufacturing color photographic materials such that a large amount of a solvent is needed in dispersing the coupler, and defects that after being dispersed in the solvent, crystallization of the coupler tends to occur. These defects are made more marked specifically under the condition of thinner coating, making it a barrier for practical application thereof.
Similarly to the benzoylacetoanilide type yellow couplers, their intermediates are also inferior in solubility in solvents so that a large amount of a solvent is needed in synthesis of the coupler, leading to deteriorated productivity thereof and increased manufacturing cost and causing problems when halogenated solvents are employed, which are superior in solubility but not preferred from the point of view of environment protection.
There have been proposed various techniques to overcome such problems. European Patent (hereinafter, denoted as EP) 327,348 discloses a technique of introducing a branched alkyl group into a benzoylacetoanilide type yellow coupler. Although this technique improved solubility, however, it exhibited the defect that dye forming efficiency is lowered when developed at a lower pH. JP-A 3-84546 (hereinafter, the term, JP-A means an unexamined and published Japanese Patent Application) and EP 897,133 also proposed introduction of a branched alkyl group. However, dye formation is still at an insufficient level and further improvements are desired.